Distributor point adjustments



Jan. 21, 1958 B. E. TOMPKINS DISTRIBUTOR POINT ADJUSTMENTS 2 Sheets-Sheet Filed July 29, 1953 INVENTOR. Bert E. Tompkins Jan. 21, 1958 B. E. TOMPKINS 2,820,858

mswazsu'rog POINT ADJUSTMENTS 1 Filed July 29, 1953 2 Sheets-Sheet 2 IIIIIIIIII/II/I/I/ A I 72 33 Fig. 5 I X 24 @v m 33 Fig. 7 33 Fig 6 IN VEN TOR.

Bert E. Tompkins Attorney United. States Patent;

DISTRIBUTOR POINT ADJUSTMENTS Bert E. Tompkins, Martinez, Calif., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application July 29, 1953, Serial No. 371,118

1 Claim. (Cl. 200-31) This invention relates to distributors and parts thereof and particularly to distributors as used in the ignition systems of internal combustion engines.

It is therefore one of the objects of this invention to provide a distributor for an internal combustion engine wherein the breaker points thereof may be adjusted externally of the distributor without in any way disturbing the operative nature thereof.

In the usual type of automotive distributor, the fixed and movable contact points thereof are adjustable only upon removal of the distributor cap. This necessitates the gauging of the contact point opening during the calibration of the point setting. It is then necessary to replace the cap in order to test the point calibration while the engine is operating. If further adjustment is required, dismantlement of the distributor is again necessary.

This procedure is time consuming and often does not provide the desired point setting of the distributor points, in view of the fact that other conditions within the ignition system have some bearing on the point setting, for example, the condition of the ignition coil, condenser, setting of the spark plugs and the like.

It is therefore highly desirable to have a distributor wherein the point setting may be made while the engine is in operative condition whereby the points may be adjusted during operation of the engine to such a calibration that the engine is operating at its best efliciency as determined by audible checking of the engine operation. It is therefore another object of this invention to provide a distributor having externally accessible adjustment means for the points, which adjustment means maybe visibly calibrated so that any specific pointopening may be arrived at by merely setting an'externally accessible dial to an indicator reading noted thereon.

A still further object of the invention is to provide a distributor having an exteriorly accessible adjustment means wherein the adjustment is made possible through a slot in the distributor housing or cover as the case may be, and wherein the plate carrying the fixed contact is predeterminedly movable by the adjustment means without in any way affecting the position of the movable contact.

In carrying out this object, the adjustment means is,

erence being had to the accompanying drawings, wherein.

a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is an external side view of a complete distributor showing one type of adjustment means thereon;

ice

removed showing the internal arrangement of breaker points, condenser, cam, etc.;

Fig. 3 is a fragmentary view of the side of the distributor showing another type of adjustment means visible through a slot in the distributor housing;

Fig. 4 is a fragmentary top view similar to Fig. 2 showing the type of adjustment means in connection with the working parts of the distributor as noted in Fig. 3;

Fig. 5 is an enlarged fragmentary view in perspective of a portion of the fixed contact member, supporting plate and adjustment means wherein certain of the parts are shown removed for clarification purposes;

Fig. 6 is a fragmentary view in section taken on line 6-6 of Fig. 5; and

Fig. 7 is a fragmentary view in section taken on line 7-7 of Fig. 5.

Referring to the drawings and particularly Fig. l, 20 designates a distributor including a housing or body 22, a cap 24, held to the body 22 by spring clips 26 and an adjustment mechanism 28. The operative connection from the distributor 20 to the engine (not shown) passes through a shaft 30 shown in the lower portion of the drawing. When the spring clips 26 are pulled from the position shown in Fig. l and the cap 24 is removed, the internal structure of the distributor appears as noted in Fig. 2 wherein a support plate assembly 32 is held within the body 22 by means of screws 34. The support plate assembly 32 is preferably of a two-piece construction which may be similar to that shown in Patent No. 2,471,318 assigned to the assignee of the present invention. In this type of a support plate, one portion 33 of the plate assembly is stationary with respect to the housing 22 and is the portion to which the screws 34 are attached, while an upper surface or plate 35 of the plate assembly is rotatable through a predetermined and limited are. It is this rotatable portion 35 of the plate that is visible in Fig. 2. The reason for the rotative mounting of the plate portion 35 is to permit movement thereof by lever 36 attached to a vacuum advance device 38. Thus, as the manifold pressures vary, the position-of the plate varies for advancing or retarding the timing of the engine. Passing through the plate 32 and centrally located therein is a cam 40 which is attached to the shaft 30 that operates in cooperation with portions of the engine (not shown). Attached to the plate 35 is a condenser 42 and a fixed contact member or plate support 44. This support 44 is pivotally mounted upon a pin 46 attached to the plate 32 and movable therewith. The amount of pivotal movement of the support 44 is controlled by a screw 48 passing through a slot therein which is spaced from the pivotal mounting so that the support plate 44 may be moved a limited distance. Also carried on the support 44 is a fixed contact member 50 preferably riveted to an up turned car 52 on the plate 44. A movable contact member 54 is also pivotally mounted on the pin 46 and carries a contact 58 at the extreme end thereon hereinafter termed the movable contact. This contact 53 cooperates with fixed contact 50 and is held in engagement therewith by means of a spring 60 that is attached to a terminal 62 that passes through the body 22. Upon the movable contact member 54 is mounted a rubbing block 64 that engages the cam 40. The setting of the points is deter mined therefore by the position of the fixed contact member 44 whereby the degree of engagement of the rubbing block 64 and the cam 40 is controlled for predetermining the distance of opening between the fixed contact 50 and the movable contact 58. It is apparent that if the fixed contact member 44 is moved toward the cam 40, the contacts will be opened wider than if the fixed contact men ber is moved away from the cam 40.

In order to limit the adjustability of the fixed contact member 44, the screw 48 is preferably shouldered as 1 10t6d i1'1,F1 g. 5' and the slot 49 in the fixed contact member is dimensioned so as to permit a predetermined degree of adjustment. In order to adjust the fixed contact member, a bifurcated stud or plate 66 is provided on the fixed contact member. This will be noted in greater detail in Figs. 5 and 6. This stud 66 may be turned up from the material of the fixed contact memher, as by punching, or it may be a separate piece of material riveted to the fixed contact member as shown. The edges of the forked portion thereon are preferably rounded. Upon the movable support plate 35 is a second stud 68 aligned with the bifurcated stud 66. Stud 68 is preferably threaded. An adjustment screw 70 passes through the stud 68 and is screw threaded to be adjustable therein and at the end thereof has a shouldered or grooved portion 72 which straddles the bifurcated portion of the stud 66. This forms a swivel con nection with respect to the stud 66 so that when the fixed contact member 44 is adjusted that there is no binding effect upon the adjustment screw 70 due to misalignment.

In order to lock the adjustment screw 70 in place, the stud 68 may be split as at 74 and slightly misaligned or the thread thereon may be tightened by squeezing the stud together at the split portion. Similarly, looking may be accomplished by disposing a coiled spring around the adjustment screw 70 and held under compression between the studs 66 and 68. Obviously, any suitable means for causing a binding or high friction eifect will provide locking of the adjustment. At the outer end of the adjustment screw 7% is provided a dial or hand knob 76 in one form of the invention. In this case, a pointer 78 is provided attached to the stud 68 and passing through a slot 80 in the distributor housing 22, which pointer acts as a fixed indicator with respect to the knob 76. On the face of the knob 76 may be inscribed any suitable indicia 82 whereby predetermined adjustments of the contact opening may be accomplished. For example, the indicia may be inscribed to any desired value in accordance with the position of the thread of the adjustment screw wherebyeach mark may represent, for example, .005" of travel.

Thus, the operator may visually adjust the points within;

by manipulating the knob externally of the distributor.

The embodiment shown in Figs. 3 and 4 is identical in most respects to the one just discussed with the exception that the knob is eliminated and a screw driver slot 84 is provided at the end of the screw which is accessilbe by means of a screw driver from the outside of the distributor through the slot 80 in the distributor housing 22. In this manner, adjustment similar to that disclosed hereinbcfore may be accomplished through the use of a screw driver. A closure member (not shown) may be provided for the slot 80.

The hold down screw 42 which maintains the fixed contact member 44 in position is shown in expanded and enlarged form in Fig. 5. This hold down screw is preferably shouldered at 43 so as to bottom against the plate 35 and still not bind against the fixed contact member 44. In order to provide a snug fit and also to frictionally maintain the fixed contact member 44 in any one position, a spring type washer 45 is provided. The one shown is of a Bclleville spring type although any crimped spring-like washer may be used, or if desired, a longer shoulder 43 may be provided on the screw 42 and a coil-type compression spring may be substituted for the washer type spring as shown, any of these deviations coming fully within the scope of my inv'ention.

In the foregoing, it will be apparent that I have provided a distributor having an exteriorly accessible adjustment means for the breaker point adjustment. This means may or may not be calibrated for visual adjustment, but in any case, is accessible from the outside of the distributor without dismantling the same whereby the contact opening may be adjusted during operating periods of the engine. The construction includes such features as a swivel connection between the adjustment screw and the fixed contact member whereby accurate adjustment may be obtained without binding, simplified locking means for maintaining the adjustment once said adjustment is completed, and the shifting of the entire fixed contact member which carries the fixed contact rather than mere adjustment of the point. in this connection, it is submitted that exterior adjustments have been proposed in the past wherein the point opening variation is obtained through a direct adjustment of the fixed contact point. It is quite apparent in this type of adjustment that the point is rotated whereby the mating surfaces of the fixed contact point and the movable contact point are changed with relation to one another whereby satisfactory electrical contact is often lost and at best, the contact of only portions of the faces of the points is obtained. In the present instance, by moving the contact member and in no way disturbing the mating relation between the faces of the points, satisfactory point operation is maintained even though the opening of the points is adjusted.

The calibrated dial is another feature of this invention which is of considerable use to the average automotive serviceman in that it is possible to determine through the dial indicia the degree of adjustment being carried out whereby over-adjustment is prevented so as to expedite the proper setting of the distributor breaker points.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted as may come within the scope of the claim which follows.

What is claimed is as follows:

A distributor for an internal combustion engine, comprising in combination; a housing including an aperture therethrough, a support plate positioned within said housing having at least a portion thereof rotatably mounted for movement within predetermined limits, a circuit breaker pivotally carried by the rotatable portion of said plate and comprising fixed and movable contacts whereby said fixed and movable contacts are translated bodily and as a unit by the rotatable portion of said support plate during rotation thereof, said fixed contact being adjustably movable relatit e to said movable contact for adjustment of contact opening therebetween, stop means cooperating with said fixed contact for limiting the extent of said adjustable movement thereof, an adjuster externally accessible of the housing for adjusting the position of the fixed contact relative to the movablecontact, said adjuster comprising a threaded stud fixedly carried by said rotatable portion of said support plate, an adjustment rod threaded through said stud and extending outwardly of the housing and through said aperture, 21 second stud spaced from and generally aligned with said threaded stud and immovable associated with said fixed contact, said second stud including a swivel connection for one end of said rod whereby a universal movement is possible between said second stud and said rod for preventing binding of the rod and stud upon pivotal movement of the fixed contact when the rod is adjustably threaded through said first mentioned stud for adjusting the position of the fixed contact, locking means associated with the threaded stud for frictionally maintaining any adjusted position of the rod in said threaded stud, whereby the position of the fixed contact may be predeterminedly adjusted with respect to the movable contact externally of the housing and maintained in said adjusted position through the action of said locking means, an indicia bearing dial located externally of the housing and carried by an end of said adjustment rod, and a pointer mounted on the threaded stud and extending outwardly of the housing through said aperture and 6 into proximity with said dial, whereby the pointer and 2,353,471 lohndrew July 11, 1944 dial are translated as a unit during rotation of the sup- 2,503,082 Tuttle Apr. 4, 1950 port plate. 2,568,162 Mohns Sept. 18, 1951 2,594,447 Kerr Apr. 29, 1952 References Cited in the file of this patent 5 2,640,891 Buck et a1, June 2, 1953 UNITED STATES PATENTS 2,048,860 Guziel et a1 July 28, 1936 

